WO2016004754A1

WO2016004754A1 - Pvdf coating material with self-cleaning property, preparation method therefor and uses thereof

Info

Publication number: WO2016004754A1
Application number: PCT/CN2015/071163
Authority: WO
Inventors: 郑玉婴; 周谦
Original assignee: 福州大学
Priority date: 2014-07-10
Filing date: 2015-01-21
Publication date: 2016-01-14
Also published as: CN104073084A

Abstract

A PVDF coating material with a self-cleaning property. The coating material consists of 10wt% to 20wt% of organic polymer, 70wt% to 80wt% of solvent, and 8wt% to 15wt% of nanoparticles as constituents. The sum of mass percentages of the constituents is 100%. The nanoparticles are TiO₂/SiO₂ nano microspheres. The coating material can coat the surface of a sheet material of PVC or PE, and the obtained coating has relatively good hydrophilia and relatively high self-cleaning property.

Description

Self-cleaning PVDF coating material and preparation method and application thereof

Technical field

The invention belongs to the field of coatings, and in particular relates to a self-cleaning PVDF coating material and a preparation method and application thereof.

Background technique

Fiber materials such as PVC and PE are widely used in the production of carports, sleeping bags and tents due to their excellent mechanical properties and good design performance. However, these materials have a prominent disadvantage - poor wear resistance, easy to be scratched, and PVC fibers are easily aging under light and hot oxygen, resulting in yellowing and stickiness of the surface of the material, not only affecting the aesthetic performance but also sticky sheets. The surface of the material easily adheres to dust and oil in the air, which makes cleaning difficult.

Through the imitation of the surface of the lotus leaf, some researchers applied a layer of PVDF on the surface of the PVC sheet. The molecular chain of PVDF contains F atoms, and the carbon chain is surrounded by F atoms, making the surface energy of PVDF small. And the crystallinity of PVDF is relatively high, and PVDF crystallized on the surface portion can form rough uneven protrusions. These protrusions can reduce the surface energy, make the contact angle larger, and play a role of hydrophobicity and protection. The dust on the surface of the PVDF is taken away by the rolling water droplets, so that the sheet has a self-cleaning function.

The surface of the hydrophobic sheet can only have a good anti-adhesion effect on hydrophilic contaminant particles, but currently a large amount of dust contains organic pollutants (NO _x /SO _x ), which are discharged through automobile exhaust gas. In the air, it is easy to get on the resin coating and it is difficult to be washed away by rain. PVDF was added in the TiO _2, TiO ₂ may be utilized in the "photo amphiphilic" to achieve better self-cleaning effect, i.e., TiO ₂ may be irradiated with ultraviolet rays in the organic substance adsorbed on the surface of the TiO ₂ photocatalytic decomposition to CO ₂ And H ₂ O, the remaining inorganic matter can be washed away by water; at the same time, the ultraviolet light can make the TiO ₂ super-hydrophilic, so that the organic matter is not easily attached to the surface.

Since the super-hydrophilicity of TiO ₂ requires ultraviolet irradiation, in actual life, the intensity of sunlight is affected by regions, seasons, and day and night, so that the super-hydrophilicity of the material becomes very high without ultraviolet rays. important. The invention utilizes TiO ₂ and SiO _{2 to} form a Ti-O-Si bond and exhibits extremely strong acidity. A certain amount of nano-SiO ₂ is further added to the coating to enhance the natural hydrophilicity of the coating.

Summary of the invention

The object of the present invention is to provide a self-cleaning PVDF coating material and a preparation method and application thereof, which are prepared by preparing nano SiO ₂ and nano TiO ₂ into TiO ₂ /SiO ₂ nano microspheres, and then with PVDF powder and solvent. Together, a new coating liquid was prepared to prepare a PVDF coating. The coating still has strong hydrophilicity in the absence of ultraviolet rays, and has a simple preparation method, high feasibility, low cost, and has strong practical significance.

To achieve the above object, the present invention adopts the following technical solutions:

A self-cleaning PVDF coating material whose composition and mass percentage of each component are as follows:

The organic polymer is 10% to 20%, the solvent is 70% to 80%, the nanoparticles are 8% to 15%, and the sum of the mass percentages of the components is 100%.

The organic polymer is PVDF.

The solvent is one or both of DMF and DMAC.

The nanoparticles are SiO ₂ /TiO ₂ nanospheres in which the Si/Ti molar ratio is 5% to 30%.

The method for preparing the self-cleaning PVDF coating material comprises the following steps:

1) mixing and stirring 5-10 ml of deionized water, 80-120 ml of absolute ethanol and 3.5-7 ml of ammonia water;

2) slowly adding 1 to 6 ml of tetraethyl orthosilicate and 8 to 16 ml of absolute ethanol to the mixture of step 1), mixing and stirring for 3 to 5 hours;

3) slowly adding 4 to 10 ml of tetrabutyl titanate and 8 to 16 ml of absolute ethanol to the mixed solution of step 2), and condensing and refluxing at 60 to 90 ° C under nitrogen for 3 to 5 hours;

4) The precipitate obtained in the step 3) is washed with absolute ethanol for 3 to 4 times, and then dried at 80 to 100 ° C for 12 to 24 hours to obtain TiO ₂ /SiO ₂ nanoparticles;

5) The nanoparticles prepared in the step 4) and 2 to 3 g of the dried PVDF powder are added to 15 to 20 ml of a solvent, and stirred at 50 to 70 ° C for 3 to 5 hours to obtain a PVDF coating material.

The self-cleaning PVDF coating material is applied by uniformly coating the coating material on the surface of a sheet of PVC, PE sheet or the like by a coating machine, and drying at 50 to 70 ° C for 15 to 30 minutes under vacuum. .

The significant advantages of the present invention are:

(1) The preparation process of the coating material of the invention is simple and the feasibility is high;

(2) Compared with the existing PVDF coating, the present invention utilizes the photocatalytic action of TiO ₂ to make the coating self-cleaning under the irradiation of sunlight; meanwhile, the introduction of SiO ₂ allows the coating to The high hydrophilicity is maintained in the absence of ultraviolet light, that is, the antifouling ability of the coating is maintained;

(3) the addition of nano-SiO ₂ can make the dispersion of TiO ₂ more uniform;

(4) In the present invention, the amount of addition of nano TiO ₂ and SiO ₂ is small, and the cost is not improved;

(5) Fiber sheets such as PVC and PE are widely used in the production of carports, sleeping bags and tents, etc., so that the invention has broad market prospects.

DRAWINGS

1 is a FE-SEM and TEM image of the TiO ₂ /SiO ₂ nanoparticles prepared in Example 1.

Figure 2 is an SEM image of the surface of a comparative TiO ₂ /PVDF coating.

3 is an FE-SEM image of the surface of the TiO ₂ /SiO ₂ /PVDF coating prepared in Example 1.

4 is a contact angle of different PVDF coatings, wherein a is a conventional PVDF, FIG. b is a comparative example of TiO ₂ /PVDF, and FIG. c is a TiO ₂ /SiO ₂ /PVDF of Example 1.

detailed description

In order to better understand the present invention, the contents of the present invention will be further clarified below with reference to the embodiments, but the contents of the present invention are not limited to the following embodiments.

Comparative example

1) mixing and stirring 5 ml of deionized water, 80 ml of absolute ethanol and 3.5 ml of ammonia water;

2) slowly adding 4 ml of tetrabutyl titanate and 8 ml of absolute ethanol to the mixed solution of step 1), and condensing and refluxing for 3 hours at 70 ° C under a nitrogen atmosphere;

3) The precipitate obtained in the step 4) is washed three times with absolute ethanol, and then vacuum dried in a vacuum drying oven at 90 ° C for 24 h to obtain TiO ₂ nanoparticles;

4) The nanoparticles prepared in the step 3) and 2 g of the dried PVDF powder were added to 18 ml of DMF solvent, and stirred at 70 ° C for 3 hours to obtain a coating material; the mass percentage of each component in the obtained coating material was as follows: PVDF20 %, DMF solvent 72%, TiO ₂ nanoparticles 8%;

5) The coating material of the step 4) was uniformly applied to the surface of the PVC tarpaulin material by a coater, vacuum dried at 70 ° C for 20 min, and then placed in a dark box for 0 days to obtain a PVDF coating.

The hydrophilicity of the TiO ₂ /PVDF coating was evaluated by a laboratory contact angle meter with a contact angle of 58° in the absence of light and a contact angle of 56° after 10 minutes of exposure to ultraviolet light.

Example 1

A method for preparing a self-cleaning PVDF coating comprises the following steps:

2) slowly adding 1 ml of tetraethyl orthosilicate and 8 ml of absolute ethanol to the mixture of step 1), and mixing and stirring for 4 hours;

3) slowly adding 4 ml of tetrabutyl titanate and 8 ml of absolute ethanol to the mixed solution of step 2), and condensing and refluxing for 3 hours at 70 ° C under nitrogen protection;

4) The precipitate obtained in the step 3) was washed with absolute ethanol for 3 times, and then vacuum dried in a vacuum drying oven at 90 ° C for 24 hours to obtain TiO ₂ /SiO ₂ nanoparticles, wherein the Si/Ti molar ratio was 10%. ;

5) The nanoparticles prepared in the step 4) and 2 g of the dried PVDF powder were added to 18 ml of DMF solvent and stirred at 70 ° C for 3 hours to obtain a PVDF coating material; the mass percentage of each component in the obtained coating material was as follows: PVDF 20%, DMF solvent 72%, TiO ₂ /SiO ₂ nanoparticles 8%;

6) The coating material of the step 5) was uniformly applied to the surface of the PVC tarpaulin material by a coater, vacuum dried at 70 ° C for 20 min, and then placed in a dark box for 0 days to obtain a self-cleaning PVDF coating.

The hydrophilicity of the TiO ₂ /SiO ₂ /PVDF coating was evaluated by a laboratory contact angle meter. The contact angle was 43° in the absence of light, and the contact angle was 38° after 10 minutes of ultraviolet light irradiation. .

Example 2

6) The coating material of the step 5) was uniformly applied to the surface of the PVC tarpaulin material by a coater, vacuum dried at 70 ° C for 20 min, and then placed in a dark box for 10 days to obtain a self-cleaning PVDF coating.

The hydrophilicity of the TiO ₂ /SiO ₂ /PVDF coating was evaluated by a laboratory contact angle meter with a contact angle of 46° in the absence of light and a contact angle of 39° after 10 minutes of exposure to ultraviolet light. .

Example 3

6) The coating material of the step 5) was uniformly applied to the surface of the PVC tarpaulin material by a coater, vacuum dried at 70 ° C for 20 min, and then placed in a dark box for 20 days to obtain a self-cleaning PVDF coating.

The hydrophilicity of the TiO ₂ /SiO ₂ /PVDF coating was evaluated by a laboratory contact angle meter. The contact angle was 50° in the absence of light, and the contact angle was 39° after 10 minutes of ultraviolet light irradiation. .

Example 4

2) slowly adding 3 ml of tetraethyl orthosilicate and 12 ml of absolute ethanol to the mixture of step 1), mixing and stirring for 4 h;

4) The precipitate obtained in the step 3) is washed three times with absolute ethanol, and then vacuum dried in a vacuum drying oven at 90 ° C for 24 hours to obtain TiO ₂ /SiO ₂ nanoparticles, wherein the Si/Ti molar ratio is 30%. ;

5) The nanoparticles prepared in the step 4) and 2 g of the dried PVDF powder were added to 18 ml of DMF solvent and stirred at 70 ° C for 3 hours to obtain a PVDF coating material; the mass percentage of each component in the obtained coating material was as follows: PVDF16%, DMF solvent 74%, TiO ₂ /SiO ₂ nanoparticles 10%;

The hydrophilicity of the TiO ₂ /SiO ₂ /PVDF coating was evaluated by a laboratory contact angle meter. The contact angle was 48° in the absence of light, and the contact angle was 48° after 10 minutes of UV irradiation. .

Example 5

3) slowly adding 6 ml of tetrabutyl titanate and 12 ml of absolute ethanol to the mixed solution of step 2), and condensing and refluxing under a nitrogen atmosphere at 70 ° C for 3 h;

4) The precipitate obtained in the step 3) was washed with absolute ethanol for 3 times, and then vacuum dried in a vacuum drying oven at 90 ° C for 24 hours to obtain TiO ₂ /SiO ₂ nanoparticles, wherein the molar ratio of Si/Ti was 7%. ;

5) The nanoparticles prepared in the step 4) and 2 g of the dried PVDF powder were added to 18 ml of DMF solvent and stirred at 70 ° C for 3 hours to obtain a PVDF coating material; the mass percentage of each component in the obtained coating material was as follows: PVDF 15%, DMF solvent 70%, TiO ₂ /SiO ₂ nanoparticles 15%;

The hydrophilicity of the TiO ₂ /SiO ₂ /PVDF coating was evaluated by a laboratory contact angle meter. The contact angle was 44° in the absence of light, and the contact angle was 39° after 10 minutes of ultraviolet light irradiation. .

Example 6

3) slowly adding 8 ml of tetrabutyl titanate and 16 ml of absolute ethanol to the mixed solution of step 2), and condensing and refluxing under a nitrogen atmosphere at 70 ° C for 3 h;

4) The precipitate obtained in the step 3) was washed three times with absolute ethanol, and then vacuum dried in a vacuum drying oven at 90 ° C for 24 hours to obtain TiO ₂ /SiO ₂ nanoparticles, wherein the molar ratio of Si/Ti was 5%. ;

5) The nanoparticles prepared in the step 4) and 2 g of the dried PVDF powder were added to 20 ml of DMF solvent and stirred at 70 ° C for 3 hours to obtain a PVDF coating material; the mass percentage of each component in the obtained coating material was as follows: PVDF 10%, DMF solvent 80%, TiO ₂ /SiO ₂ nanoparticles 10%;

The hydrophilicity of the TiO ₂ /SiO ₂ /PVDF coating was evaluated by a laboratory contact angle meter, the contact angle was 45° in the absence of light, and the contact angle was 42° after 10 minutes of ultraviolet light irradiation. .

1 is a FE-SEM and TEM image of the TiO ₂ /SiO ₂ nanoparticles prepared in Example 1. The core structure of TiO ₂ /SiO ₂ can be clearly seen from FIG.

The invention introduces TiO ₂ /SiO ₂ nanospheres into a conventional PVDF coating to prepare a coating material having better hydrophilicity and stronger self-cleaning property. Through experimental comparison, we found that the introduction of SiO ₂ in the TiO ₂ /PVDF coating, when the ratio of Si / Ti molar ratio is lower (<30%), the hydrophilicity of the coating is significantly reduced, even in the absence of light. 20 days still have good hydrophilicity, and the hydrophilicity of the coating immediately recovers under ultraviolet light irradiation; but when the ratio of Si/Ti molar ratio is low (<5%), it may be due to TiO ₂ agglomeration decreased so that the photocatalytic action; when the ratio is higher molar ratio of Si Ti / (> 30%), the coating still has a certain hydrophilic nature, but will destroy the crystalline structure _of TiO, resulting in loss of photocatalytic TiO ₂ effect.

The above description is only a preferred embodiment of the present invention, and all the equivalent changes and modifications made according to the scope of the patent application of the present invention should be It is within the scope of the invention.

Claims

A self-cleaning PVDF coating material characterized in that the composition of the coating material and the mass percentage of each component are as follows:

The organic polymer is 10% to 20%, the solvent is 70% to 80%, the nanoparticles are 8% to 15%, and the sum of the mass percentages of the components is 100%.
A self-cleaning PVDF coating material according to claim 1, wherein the organic polymer is PVDF.
The self-cleaning PVDF coating material according to claim 1, wherein the solvent is one or both of DMF and DMAC.
The self-cleaning PVDF coating material according to claim 1, wherein the nanoparticles are SiO 2 /TiO 2 nanospheres, wherein the Si/Ti molar ratio is 5% to 30%.
A method for preparing a self-cleaning PVDF coating material according to claim 1, comprising the steps of:

1) mixing and stirring 5-10 ml of deionized water, 80-120 ml of absolute ethanol and 3.5-7 ml of ammonia water;

2) slowly adding 1 to 6 ml of tetraethyl orthosilicate and 8 to 16 ml of absolute ethanol to the mixture of step 1), mixing and stirring for 3 to 5 hours;

3) slowly adding 4 to 10 ml of tetrabutyl titanate and 8 to 16 ml of absolute ethanol to the mixed solution of step 2), and condensing and refluxing at 60 to 90 ° C under nitrogen for 3 to 5 hours;

4) The precipitate obtained in the step 3) is washed with absolute ethanol for 3 to 4 times, and then dried at 80 to 100 ° C for 12 to 24 hours to obtain nanoparticles;

5) The nanoparticles prepared in the step 4) and 2 to 3 g of the dried PVDF powder are added to 15 to 20 ml of a solvent, and stirred at 50 to 70 ° C for 3 to 5 hours to obtain a PVDF coating material.
The invention relates to a self-cleaning PVDF coating material according to claim 1, wherein the coating material is uniformly applied to the surface of the sheet by a film coating machine, and vacuum dried at 50 to 70 ° C. 15 to 30 minutes.
Use of a self-cleaning PVDF coating material according to claim 6 wherein the sheet comprises a PVC sheet and a PE sheet.